Pseudomonas aeruginosa infection
Pseudomonas aeruginosa is a nosocomial, opportunistic gram-negative bacillus that causes hot-tub folliculitis, malignant otitis externa, ventilator-associated pneumonia, febrile-neutropenia bacteremia with ecthyma gangrenosum, and device-associated infections. Empiric therapy requires an antipseudomonal agent and, in resistance-risk or unstable patients, double coverage until susceptibilities return.
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What this article covers
- Overview
Opportunistic, nosocomial gram-negative bacillus: Pseudomonas aeruginosa causes disease predominantly in hospitalized, immunocompromised, or device-exposed hosts rather than healthy outpatients.
- Epidemiology
Health care setting predominance: infection is concentrated in hospitals, intensive care units, and long-term acute care facilities, where multidrug-resistant organisms are most prevalent.
- Risk factors
Neutropenia: absolute neutrophil count decline from cytotoxic chemotherapy is the single highest-risk state for Pseudomonas infection and bacteremia.
- Pathophysiology
Opportunistic invasion through breached barriers: cytotoxic chemotherapy and mucositis breach mucosal and cutaneous defenses, allowing translocation of gut or skin flora into the bloodstream.
- Clinical features
Fever with hemodynamic instability in a neutropenic patient: the presenting picture of Pseudomonas bacteremia; a source is identified in only a minority of patients, so any febrile neutropenic patient is presumed at risk.
- Differential diagnosis
Staphylococcus aureus infection (including MRSA): overlapping presentation in folliculitis, bacteremia, osteomyelitis, and pneumonia; the discriminator is Gram stain showing gram-positive cocci in clusters, not gram-negative rods.
- Diagnosis
Culture establishes the diagnosis: there is no formal criteria set for Pseudomonas infection; confirmation rests on isolation of P aeruginosa from a clinically relevant specimen (blood, bone, deep…
- Management
Start empiric antipseudomonal therapy immediately in any febrile neutropenic or hemodynamically unstable patient with suspected Pseudomonas infection, before culture results return.
- Complications
Septic shock and multiorgan failure: the most life-threatening complication of Pseudomonas bacteremia, particularly in neutropenic patients.
- Prognosis
Multidrug-resistant Pseudomonas infection carries mortality up to four times higher than antibiotic-sensitive infection.
- Prevention
Ventilator bundle adherence reduces VAP incidence by 21%: elevate the head of the bed 30 to 45 degrees, provide daily sedation interruption with extubation-readiness assessment, use subglottic…
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